Coronavirus is believed to cause a large percentage of all common colds in adults, especially in winter and early spring. It was first isolated from chickens in 1937 by Beaudette and Hudson. In 1965, Tyrrell and Bynoe used cultures of human ciliated embryonic trachea to propagate the first human coronavirus in vitro.
Among the more than 30 strains isolated so far, three or four infect humans. For example, the severe acute respiratory syndrome, a newly emerging infectious disease, is associated with a novel coronavirus (Ksiazek et al., New England Journal Medicine, 2003, 348(20): 1953-1966). This life-threatening respiratory virus has caused worldwide outbreaks in 2003.